The Parliament of the Daleks referred to the ruling body of the New Dalek Paradigm and the large spaceship that housed them. It consisted of an immense number of Daleks, including thousands of bronze Daleks, several red Drone Daleks, a blue Strategist Dalek and a white Supreme Dalek, headed by their Prime Minister.
Research by historians who studied the Dalek race theorised that an incarnation of Parliament of the Daleks had existed during the era of the Dalek Empire. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) Indeed, the "Dalek Parliament" existed on Skaro by 2223. They contacted the Dalek Litigator on Earth so that he could relay the decision to abort the attempted re-invasion of Earth; the Litigator transmitted those orders directly to the Dalek warriors, bypassing the Dalek Supreme leading the invasion, to the latter's ire. (AUDIO: Vengeance)
Several accounts, such as A Short Treatise on Dalek Justice by Benncuiq IV, (PROSE: The Runes of Fenric) suggested that the trial of the Master, (TV: Doctor Who) for his failure in their mutual involvement in the Human-Draconian War, (TV: Frontier in Space; PROSE: The Runes of Fenric) had been overseen by the Parliament. (PROSE: The Runes of Fenric, Dalek: The Astounding Untold History of the Greatest Enemies of the Universe) The Master was found guilty, and executed by the Dalek Prelature, (AUDIO: Mastermind) although another account claimed that his execution was overseen by only one Dalek, (PROSE: The Curse of Fenric) while a third account claimed that the Dalek Litigator had overseen the Master's execution. (AUDIO: Vengeance)
After the Eleventh Doctor had defeated the New Dalek Paradigm several times, the Daleks underwent a reorganisation, reestablishing the Parliament, led by the Prime Minister of the Daleks instead of being ruled by an Emperor. The deliberations of the Parliament were largely kept a secret, only snippets being uploaded to the Pathweb and taking place on a large saucer named "Nacrana Va Hateen", which roughly translated as "The Highest Authority". The five original founders of the New Dalek Paradigm maintained a token presence in the Parliament but, as a result of their repeated failures, had little power. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)
The Prime Minister of the Daleks ordered the abduction of the Eleventh Doctor and his companions Amy Pond and Rory Williams, summoning them to the Parliament of the Daleks and granting them a mission to lower the indestructible force field of the Dalek Asylum because they had noticed the spaceship Alaska crashland into the planet, and they were afraid the insane Daleks interned in the asylum might escape.
Once this had been achieved by Oswin Oswald (a human-turned-Dalek), the Parliament launched numerous missiles and successfully destroyed the entire planet. But just beforehand, Oswin erased all information about the Doctor from the pathweb (memory) of the New Dalek Paradigm. The members of the Parliament were therefore unable to recognise him when the Doctor teleported onto the vessel, and they repeatedly asked the Question: "Doctor Who?". Moments before the Doctor escaped from their vessel in his TARDIS, he recognised this was a watershed moment in his history with his worst enemies, and he thanked Oswin for accomplishing this. (TV: Asylum of the Daleks)
This gap in the Daleks' memory crippled the Parliament as they debated how to proceed, halting the Daleks' perpetual war effort. When the Question was heard from Trenzalore, the Parliament sent a fleet to investigate where it was found that the signal was the Time Lords. After the Siege of Trenzalore had waged for three centuries, the Daleks attacked the Papal Mainframe, who enforced an uneasy truce, directly, harvesting the memories of Tasha Lem. The memories were remotely beamed to the Parliament with the Prime Minister being driven mad by the returned memory of the Doctor. Declaring it unfit for duty, the Dalek Supreme exterminated the Prime Minister and became the Parliament's new leader.
After a further five centuries of war, the Daleks had broken through Trenzalore's defences, with the Supreme ordering The Highest Authority to the planet so it could personally exterminate the Doctor only for the Time Lords to grant the Doctor a new cycle of regenerations. The energy released by this was so great that it reduced the Parliament to atoms, historians even believing that the Parliament's fall might have been the final defeat of the Daleks. (TV: The Time of the Doctor; PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)